Bulk nickel-cobalt-based glasses bearing chromium, tantalum, phosphorus and boron

ABSTRACT

Ni—Co—Cr—Ta—P—B alloys and metallic glasses with controlled ranges are provided. The alloys demonstrate a combination of good glass forming ability, high toughness, and high stability of the supercooled liquid. The disclosed alloys are capable of forming metallic glass rods of diameters at least 3 mm and up to about 8 mm or greater. Certain alloys with good glass forming ability also have high notch toughness approaching 100 MPa m 1/2 , and stability of the supercooled liquid approaching 60° C.

TECHNICAL FIELD

The present disclosure relates to Ni—Co—Cr—Ta—P—B alloys capable of forming metallic glass with critical rod diameters of at least 3 mm and as large as 8 mm or larger.

BACKGROUND

Ni—Cr—Ta—P—B alloys with critical rod diameters of 3 mm or larger have been disclosed in U.S. patent application Ser. No. 14/081,622, entitled “Bulk Nickel-Phosphorus-Boron Glasses Bearing Chromium Tantalum”, filed on Nov. 15, 2013, the disclosure of which is incorporated herein by reference in its entirety. In this application, bulk glass forming ability is identified for Cr content ranging from 3 to 11 atomic percent, Ta content ranging from 1.75 to 4 atomic percent, P content ranging from 14 to 17.5 atomic percent, and B content ranging from 2.5 to 5 atomic percent. Bulk metallic glasses rods with critical rod diameters as large as 7 mm can be formed within those ranges.

Although the application states that Ni or Cr substitution by Co of up to 2 atomic percent may not impair the glass forming ability of the disclosed alloys, it does not address the potential of glass formation of Ni—Co—Cr—Ta—P—B alloys, where Co concentrations of up to 40 atomic percent are included.

BRIEF SUMMARY

The present disclosure is directed to Ni—Co—Cr—Ta—P—B alloys and metallic glasses comprising Ni—Co—Cr—Ta—P—B alloys, where Co is included in concentrations of up to 40 atomic percent. The alloys have critical rod diameters of at least 3 mm and up to 8 mm or larger. In some embodiments, the metallic glasses may also exhibit notch toughness values in excess of 90 MPa m^(1/2).

In one embodiment, the disclosure provides an alloy or a metallic glass formed of an alloy represented by the following formula (subscripts denote atomic percent):

Ni_((100-a-b-c-d-e))Co_(a)Cr_(b)Ta_(c)P_(a)B_(e)   Eq. (1)

where:

a ranges from 0.5 to 40

b ranges from 3 to 11

c ranges from 1.5 to 4

d ranges from 14 to 17.5

e ranges from 2 to 5.

In various aspects, the critical rod diameter of the alloys is at least 3 mm.

In another embodiment, c is determined by x+y·b, where x is between 1.5 and 2 and y is between 0.1 and 0.15.

In another embodiment, a ranges from 0.5 to 30, b ranges from 8 to 10.5, c ranges from 2.25 to 3.75, d ranges from 15.5 to 17, e ranges from 2.5 to 4. In various aspects, the critical rod diameter of the alloy is at least 5 mm.

In another embodiment, a ranges from 0.5 to 15, b ranges from 8.5 to 10, c ranges from 2.5 to 3.5, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75. In various aspects, the critical rod diameter of the alloy is at least 6 mm.

In another embodiment, a ranges from 0.5 to 30, b ranges from 6 to 8, c ranges from 2 to 3.5, d ranges from 15.5 to 17, e ranges from 2.5 to 4. In various aspects, the critical rod diameter of the alloy is at least 5 mm.

In another embodiment, a ranges from 0.5 to 5, b ranges from 6.5 to 7.5, c ranges from 2.25 to 3.25, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75. In various aspects, the critical rod diameter of the alloy is at least 6 mm.

In another embodiment, a ranges from 0.5 to 15, b ranges from 8.5 to 10, c ranges from 2.5 to 3.5, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75, In various aspects, the critical rod diameter of the alloy is at least 6 mm. In other aspects, the notch toughness, defined as the stress intensity factor at crack initiation when measured on a 3 mm diameter rod containing a notch with length ranging from 1 to 2 mm and root radius ranging from 0.1 to 0.15 mm, is at least 55 MPa m^(1/2).

In another embodiment, a ranges from 0.5 to 5, b ranges from 6.5 to 7.5, c ranges from 2.25 to 3.25, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75. In various aspects, the critical rod diameter of the alloy is at least 6 mm. In other aspects the notch toughness, defined as the stress intensity factor at crack initiation when measured on a 3 mm diameter rod containing a notch with length ranging from 1 to 2 mm and root radius ranging from 0.1 to 0.15 mm, is at least 80 MPa m^(1/2).

In another embodiment, a ranges from 0.5 to 10, b ranges from 8.5 to 10, c ranges from 2.5 to 3.5, d ranges from 15.75 to 16.75, and e ranges from 2.75 to 3.75. In various aspects, the critical rod diameter of the alloy is at least 6 mm. In other aspects, the notch toughness, defined as the stress intensity factor at crack initiation when measured on a 3 mm diameter rod containing a notch with length ranging from 1 to 2 mm and root radius ranging from 0.1 to 0.15 mm, is at least 60 MPa m^(1/2).

In another embodiment, a ranges from 0.5 to 3, b ranges from 6.5 to 7.5, c ranges from 2.25 to 3.25, d ranges from 15.75 to 16.75, and e ranges from 2.75 to 3.75. In various aspects, the critical rod diameter of the alloy is at least 7 mm. In other aspects the notch toughness, defined as the stress intensity factor at crack initiation when measured on a 3 mm diameter rod containing a notch with length ranging from 1 to 2 mm and root radius ranging from 0.1 to 0.15 mm, is at least 90 MPa m^(1/2).

In another embodiment, the difference between the crystallization temperature T_(x) and the glass transition temperature T_(g), ΔT_(x)=T_(x)−T_(g), measured at heating rate of 20 K/min, is at least 42° C.

In another embodiment, the difference between the crystallization temperature T_(x) and the glass transition temperature T_(g), ΔT_(x)=T_(x)−T_(g), measured at heating rate of 20 K/min, is at least 50° C.

In another embodiment, a ranges from 4 to 30, b ranges from 8 to 10.5, c ranges from 2.25 to 3.75, d ranges from 15.5 to 17, e ranges from 2.5 to 4, and wherein the alloy has a critical rod diameter of at least 5 mm, and wherein the difference between the crystallization temperature T_(x) and the glass transition temperature T_(g), ΔT_(x)=T_(x)−T_(g), measured at heating rate of 20 K/min, is at least 50° C.

In another embodiment, a ranges from 4 to 30, b ranges from 6 to 8, c ranges from 2 to 3.5, d ranges from 15.5 to 17, e ranges from 2.5 to 4, and wherein the critical rod diameter of the alloy is at least 5 mm, and wherein the difference between the crystallization temperature T_(x) and the glass transition temperature T_(g), ΔT_(x)=T_(x)−T_(g), measured at heating rate of 20 K/min, is at least 45° C.

In yet another embodiment, up to 2 atomic percent of Cr is substituted by Fe, Mn, W, Mo, Ru, Re, Cu, Pd, Pt, or combinations thereof.

In yet another embodiment, up to 2 atomic percent of Ni is substituted by Fe, Mn, W, Mo, Ru, Re, Cu, Pd, Pt, or combinations thereof.

In yet another embodiment, up to 1.5 atomic percent of Ta is substituted by Nb, V, or combinations thereof.

In yet another embodiment, the melt of the alloy is fluxed with a reducing agent prior to rapid quenching.

In yet another embodiment, the melt of the alloy is fluxed with boron oxide prior to rapid quenching.

In yet another embodiment, the temperature of the melt prior to quenching is at least 100° C. above the liquidus temperature of the alloy.

In yet another embodiment, the temperature of the melt prior to quenching is at least 1100° C.

The disclosure is also directed to an alloy having composition selected from a group consisting of: Ni₆₇Co_(1.5)Cr₉Ta₃P_(16.25)B_(3.25), Ni_(65.5)CO₃Cr₉Ta₃P_(16.25)B_(3.25), Ni_(63.5)CO₅Cr₉Ta₃P_(16.25)B_(3.25), Ni_(58.5)CO₁₀Cr₉Ta₃P_(16.25)B_(3.25), Ni_(53.5)Co₁₅Cr₉Ta₃P_(16.25)B_(3.25), Ni_(48.5)CO₂₀Cr₉Ta₃P_(16.25)B_(3.25), Ni_(43.5)Co₂₅Cr₉Ta₃P_(16.25)B_(3.25), Ni_(38.5)CO₃₀Cr₉Ta₃P_(16.25)B_(3.25), Ni_(33.5)CO₃₅Cr₉Ta₃P_(16.25)B_(3.25), Ni_(28.5)Co₄₀Cr₉Ta₃P_(16.25)B_(3.25), Ni_(70.5)Cr₇Ta_(2.75)P_(16.25)B_(3.25), Ni₆₉Co_(1.5)Cr₇Ta_(2.75)P_(16.25)B_(3.25), Ni_(67.5)CO₃Cr₇Ta_(2.75)P_(16.25)B_(3.25), Ni_(65.5)CO₅Cr₇Ta_(2.75)P_(16.25)B_(3.25), Ni_(60.5)Co₁₀Cr₇Ta_(2.75)P_(16.25)B_(3.25), Ni_(55.5)Co₁₅Cr₇Ta_(2.75)P_(16.25)B_(3.25), Ni_(50.5)CO₂₀Cr₇Ta_(2.75)P_(16.25)B_(3.25), Ni_(45.5)CO₂₅Cr₇Ta_(2.75)P_(16.25)B_(3.25), Ni_(40.5)CO₃₀Cr₇Ta_(2.75)P_(16.25)B_(3.25), NI_(45.5)CO₃₅Cr₇Ta_(2.75)P_(16.25)B_(3.25), and Ni_(30.5)Co₄₀Cr₇Ta_(2.75)P_(16.25)B_(3.25). In various aspects, the critical rod diameter of the alloy is at least 3 mm.

In a further embodiment, a method is provided for forming a metallic glass object having a lateral dimension of at least 3 mm. The method includes melting an alloy into a molten state, the alloy comprising at least Ni, Co, Cr, Ta, P, and B with a formula Ni_((100-a-b-c-d-e))Co_(a)Cr_(b)Ta_(c)P_(c)/B_(e), wherein a ranges from 0.5 to 40, b ranges from 3 to 11, c ranges from 1.5 to 4, d ranges from 14 to 17.5, and e ranges from 2 to 5. The method also includes quenching the molten alloy at a cooling rate sufficiently rapid to prevent crystallization of the alloy.

The disclosure is further directed to a metallic glass having any of the above formulas and/or formed of any of the foregoing alloys.

Additional embodiments and features are set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the specification or may be learned by the practice of the disclosed subject matter. A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings, which forms a part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The description will be more fully understood with reference to the following figures and data graphs, which are presented as various embodiments of the disclosure and should not be construed as a complete recitation of the scope of the disclosure.

FIG. 1 provides a data plot showing the effect of varying the Ni and Co atomic percent on the glass forming ability of Ni_(68.5-x)Co_(x)Cr₉Ta₃P_(16.25)B_(3.25) alloys, in accordance with embodiments of the present disclosure, for 0≦x≦45.

FIG. 2 provides a data plot showing the effect of varying the Ni and Co atomic percent on the notch toughness of Ni_(68.5-x)Co_(x)Cr₉Ta₃P_(16.25)B_(3.25) metallic glasses, in accordance with embodiments of the present disclosure, for 0≦x≦45.

FIG. 3 provides an X-ray diffractogram verifying the amorphous structure of a 8 mm rod of a sample metallic glass Ni_(65.5)Co₃Cr₉Nb₃P_(16.25)B_(3.25), in accordance with embodiments of the present disclosure, processed by water quenching the high temperature melt in a fused silica tube having a wall thickness of 1 mm.

FIG. 4 provides a data plot showing the effect of varying the Ni and Co atomic percent on the glass forming ability of Ni_(70.5-x)Co_(x)Cr₇Ta_(2.75)P_(16.25)B_(3.25) alloys, in accordance with embodiments of the present disclosure, for 0≦x≦45.

FIG. 5 provides a data plot showing the effect of varying the Ni and Co atomic percent on the notch toughness of Ni_(70.5-x)Co_(x)Cr₇Ta_(2.75)P_(16.25)B_(3.25) metallic glasses, in accordance with embodiments of the present disclosure, for 0≦x≦45.

FIG. 6 provides calorimetry scans for sample metallic glasses Ni_(68.5-x)Co_(x)Cr₉Ta₃P_(16.25)B_(3.25) in accordance with embodiments of the present disclosure. The glass transition temperature T_(g), crystallization temperature T_(x), solidus temperature T_(s), and liquidus temperature T_(l) are indicated by arrows.

FIG. 7 provides a data plot showing the effect of varying the Ni and Co atomic percent on the glass transition temperature T_(g), crystallization temperature T_(x), and difference ΔT_(x)=T_(x)−T_(g) of Ni_(68.5-x)Co_(x)Cr₉Ta₃P_(16.25)B_(3.25) metallic glasses, in accordance with embodiments of the present disclosure, for 0≦x≦40.

FIG. 8 provides calorimetry scans for sample metallic glasses Ni_(70.5-x)Co_(x)Cr₇Ta_(2.75)P_(16.25)B_(3.25) in accordance with embodiments of the present disclosure. The glass transition temperature T_(g), crystallization temperature T_(x), solidus temperature T_(s), and liquidus temperature T_(l) are indicated by arrows.

FIG. 9 provides a data plot showing the effect of varying the Ni and Co atomic percent on the glass transition temperature T_(g), crystallization temperature T_(x), and difference ΔT_(x)=T_(x)−T_(g) of Ni_(70.5-x)Co_(x)Cr₇Ta_(2.75)P_(16.25)B_(3.25) metallic glasses, in accordance with embodiments of the present disclosure, for 0≦x≦40.

DETAILED DESCRIPTION

The present disclosure is directed to alloys, metallic glasses, and methods of making and using the same. In some aspects, the alloys are described as capable of forming metallic glasses having certain characteristics. It is intended, and will be understood by those skilled in the art, that the disclosure is also directed to metallic glasses formed of the disclosed alloys described herein.

Definitions

In the present disclosure, the glass-forming ability of each alloy is quantified by the “critical rod diameter,” defined as the largest rod diameter in which the amorphous phase (i.e. the metallic glass) can be formed when processed by a method of water quenching a quartz tube having 0.5 mm thick walls containing a molten alloy.

A “critical cooling rate”, which is defined as the cooling rate required to avoid crystallization and form the amorphous phase of the alloy (i.e. the metallic glass), determines the critical rod diameter. The lower the critical cooling rate of an alloy, the larger its critical rod diameter. The critical cooling rate R_(c) in K/s and critical rod diameter d_(c) in mm are related via the following approximate empirical formula:

R_(c)=1000/d _(c) ²   Eq. (2)

According to Eq. (2), the critical cooling rate for an alloy having a critical rod diameter of about 3 mm, as in the case of the alloys according to embodiments of the present disclosure, is only about 10² K/s.

Generally, three categories are known in the art for identifying the ability of an alloy to form glass (i.e. to bypass the stable crystal phase and form an amorphous phase). Alloys having critical cooling rates in excess of 10¹² K/s are typically referred to as non-glass formers, as it is physically impossible to achieve such cooling rates over a meaningful thickness (i.e. at least 1 micrometer). Alloys having critical cooling rates in the range of 10⁵ to 10¹² K/s are typically referred to as marginal glass formers, as they are able to form glass over thicknesses ranging from 1 to 100 micrometers according to Eq. (2). Alloys having critical cooling rates on the order of 10³ or less, and as low as 1 or 0.1 K/s, are typically referred to as bulk glass formers, as they are able to form glass over thicknesses ranging from 1 millimeter to several centimeters. The glass-forming ability of a metallic alloy is, to a very large extent, dependent on the composition of the alloy. The compositional ranges for alloys capable of forming marginal glass formers are considerably broader than those for forming bulk glass formers.

The “notch toughness,” defined as the stress intensity factor at crack initiation K_(q), when measured on a 3 mm diameter rod containing a notch with length ranging from 1 to 2 mm and rot radius ranging from 0.1 to 0.15mm, is the measure of the material's ability to resist fracture in the presence of a notch. The notch toughness is a measure of the work required to propagate a crack originating from a notch. A high K_(q) ensures that the material will be tough in the presence of defects.

The width of the supercooled region ΔT_(x) is defined as the difference between the crystallization temperature T_(x) and the glass transition temperature T_(g) of the metallic glass, ΔT_(x)=T_(x)−T_(g), measured at heating rate of 20 K/min. A large ΔT_(x) value designates an ability of the metallic glass to be formed into an article by thermoplastic processing at temperatures above T_(g).

Description of Alloy Compositions and Metallic Glass Compositions

In accordance with the provided disclosure and drawings, Ni—Co—Cr—Ta—P—B alloys and metallic glasses of Ni—Co—Cr—Ta—P—B alloys are provided within a well-defined compositional range requiring very low cooling rates to form metallic glasses, thereby allowing for bulk metallic glass formation such that metallic glass rods with critical rod diameters of at least 3 mm can be formed.

In some embodiments, Ni—Co—Cr—Ta—P—B alloys that fall within the compositional ranges of the disclosure can be represented by the following formula (subscripts denote atomic percent):

Ni_((100-a-b-c-d-e))Co_(a)Cr_(b)Ta_(c)P_(a)B_(e)   Equation (1)

where a ranges from 0.5 to 40, b ranges from 3 to 11, c ranges from 1.5 to 4, d ranges from 14 to 17.5, and e ranges from 2 to 5.

In various aspects, the critical rod diameter of the alloy is at least 3 mm.

Samples of metallic glasses comprising alloys with compositions according to the formula Ni_(68.5-x)Co_(x)Cr₉Ta₃P_(16.25)B_(3.25), in accordance with embodiments of the present disclosure, are presented in Table 1. The critical rod diameters of sample alloys, along with the notch toughness of corresponding metallic glasses, are also listed in Table 1. Sample 1 with composition Ni_(68.6)Cr₈Nb₃P_(16.25)B_(3.25) is free of Co and is disclosed in U.S. patent application Ser. No. 14/081,622, exhibiting a critical rod diameter of 7 mm and a notch toughness of 51.8 MPa m^(1/2).

TABLE 1 Sample alloys demonstrating the effect of increasing the Co atomic concentration at the expense of Ni on the glass forming ability and notch toughness of Ni_(68.5−x)CO_(x)Cr₉Ta₃P_(16.25)B_(3.25) alloys Sam- Critical Rod Notch Toughness ple Composition Diameter [mm] K_(Q) (MPa m^(1/2)) 1 Ni_(68.5)Cr₉Ta₃P_(16.25)B_(3.25) 7 51.8 ± 4.8 2 Ni₆₇Co_(1.5)Cr₉Ta₃P_(16.25)B_(3.25) 7  76.5 ± 11.0 3 Ni_(65.5)Co₃Cr₉Ta₃P_(16.25)B_(3.25) 8 71.5 ± 2.9 4 Ni_(63.5)Co₅Cr₉Ta₃P_(16.25)B_(3.25) 7 63.7 ± 3.2 5 Ni_(58.5)Co₁₀Cr₉Ta₃P_(16.25)B_(3.25) 6  67.0 ± 10.0 6 Ni_(53.5)Co₁₅Cr₉Ta₃P_(16.25)B_(3.25) 6 58.0 ± 5.6 7 Ni_(48.5)Co₂₀Cr₉Ta₃P_(16.25)B_(3.25) 5 40.2 ± 1.0 8 Ni_(43.5)Co₂₅Cr₉Ta₃P_(16.25)B_(3.25) 5 45.7 ± 2.1 9 Ni_(38.5)Co₃₀Cr₉Ta₃P_(16.25)B_(3.25) 5 38.2 ± 0.3 10 Ni_(33.5)Co₃₅Cr₉Ta₃P_(16.25)B_(3.25) 4 31.5 ± 5.0 11 Ni_(28.5)Co₄₀Cr₉Ta₃P_(16.25)B_(3.25) 3 — 12 Ni_(23.5)Co₄₅Cr₉Ta₃P_(16.25)B_(3.25) 1 —

FIG. 1 provides a data plot showing the effect of varying the Ni and Co atomic content x on the glass forming ability of alloys according to the composition formula Ni_(68.5-x)Co_(x)Cr₉Ta₃P_(16.25)B_(3.25). FIG. 2 provides a data plot showing the effect of varying the Ni and Co atomic content x on the notch toughness of metallic glasses according to the composition formula Ni_(69-x)Co_(x)Cr_(8.5)Nb₃P_(16.5)B₃.

As shown in Table 1 and FIG. 1, alloys that satisfy the disclosed compositional range given by Eq (1) demonstrate a critical rod diameter of at least 3 mm. Also, as shown in Table 1 and FIGS. 1 and 2, when Co varies between 0.5 and 3 atomic percent, both the glass forming ability of the alloy and notch toughness of the metallic glass unexpectedly increase as compared to the Co-free alloy and metallic glass. Alloys and metallic glasses, according to the composition formula Ni_(68.5-x)Co_(x)Cr₉Ta₃P_(16.25)B_(3.25,) with Co content between 0.5 and 3 atomic percent provide a good combination of high toughness and good glass forming ability. Specifically, alloy Ni_(65.5)Co₃Cr₉Ta₃P_(16.25)B_(3.25) (Sample 3) demonstrates a critical rod diameter of 8 mm and notch toughness of 71.5 MPa m^(1/2), while the Co-free alloy Ni_(68.5)Cr₉Ta₃P_(16.25)B_(3.25) (Sample 1) demonstrates a critical rod diameter of 7 mm and notch toughness of 51.8 MPa m^(1/2).

FIG. 3 provides an X-ray diffractogram verifying the amorphous structure of an 8 mm rod of sample metallic glass Ni_(65.5)Co₃Cr₉Ta₃P_(16.25)B_(3.25) (Sample 3) processed by water quenching the high temperature melt in a fused silica tube having a wall thickness of 1 mm.

Samples metallic glasses comprising alloys with compositions according to the formula Ni_(70.5-x)Co_(x)Cr₇Ta_(2.75)P_(16.25)B_(3.25) are presented in Table 2. The critical rod diameters of the sample alloys, along with the notch toughness of the corresponding metallic glasses, are also listed in Table 2. Sample 13 with composition Ni_(70.5)Cr₇Ta_(2.75)P_(16.25)B_(3.25) is free of Co and is disclosed in the U.S. patent application Ser. No. 14/081,622, exhibiting a critical rod diameter of 7 mm and a notch toughness of 79.3 MPa m^(1/2).

TABLE 2 Sample alloys demonstrating the effect of increasing the Co atomic concentration at the expense of Ni on the glass forming ability and notch toughness of Ni_(70.5−x)Co_(x)Cr₇Ta_(2.75)P_(16.25)B_(3.25) alloys Sam- Critical Rod Notch Toughness ple Composition Diameter [mm] K_(Q) (MPa m^(1/2)) 13 Ni_(70.5)Cr₇Ta_(2.75)P_(16.25)B_(3.25) 7 79.3 ± 5.6 14 Ni₆₉Co_(1.5)Cr₇Ta_(2.75)P_(16.25)B_(3.25) 7 94.4 ± 3.8 15 Ni_(67.5)Co₃Cr₇Ta_(2.75)P_(16.25)B_(3.25) 7 90.7 ± 0.5 16 Ni_(65.5)Co₅Cr₇Ta_(2.75)P_(16.25)B_(3.25) 6 74.5 ± 8.6 17 Ni_(60.5)Co₁₀Cr₇Ta_(2.75)P_(16.25)B_(3.25) 5 45.9 ± 4.6 18 Ni_(55.5)Co₁₅Cr₇Ta_(2.75)P_(16.25)B_(3.25) 5 58.4 ± 2.0 19 Ni_(50.5)Co₂₀Cr₇Ta_(2.75)P_(16.25)B_(3.25) 4 48.7 ± 3.0 20 Ni_(45.5)Co₂₅Cr₇Ta_(2.75)P_(16.25)B_(3.25) 4  44.9 ± 12.3 21 Ni_(40.5)Co₃₀Cr₇Ta_(2.75)P_(16.25)B_(3.25) 5 35.5 ± 9.2 22 Ni_(45.5)Co₃₅Cr₇Ta_(2.75)P_(16.25)B_(3.25) 3 — 23 Ni_(30.5)Co₄₀Cr₇Ta_(2.75)P_(16.25)B_(3.25) 2 — 24 Ni_(25.5)Co₄₅Cr₇Ta_(2.75)P_(16.25)B_(3.25) 1 —

FIG. 4 provides a data plot showing the effect of varying the Ni and Co atomic content x on the glass forming ability of alloys according to the composition formula Ni_(70.5-x)Co_(x)Cr₇Ta_(2.75)P_(16.25)B_(3.25). FIG. 5 provides a data plot showing the effect of varying the Ni and Co atomic percent x on the notch toughness of metallic glasses according to the composition formula Ni_(70.5-x)Co_(x)Cr₇Ta_(2.75)P_(16.25)B_(3.25).

Also, as shown in Table 2 and FIGS. 4 and 5, when Co varies between 0.5 and 3 atomic percent, the notch toughness of the metallic glass unexpectedly increases as compared to the Co-free alloy and metallic glass, while the glass forming ability remains unchanged. Specifically, alloy Ni₆₉Co_(1.5)Cr₇Ta_(2.75)P_(16.25)B_(3.25) (Sample 14) demonstrates a notch toughness of 94.4 MPa m^(1/2) and a critical rod diameter of 7 mm, while the Co-free alloy Ni_(70.5)Cr₇Ta_(2.75)P_(16.25)B_(3.25) (Sample 13) demonstrates a notch toughness of 93.9 MPa m^(1/2) and a critical rod diameter of 7 mm.

In other embodiments, Ni—Co—Cr—Ta—P—B metallic glasses according to Eq 1 of the present disclosure exhibit a difference between the crystallization temperature T_(x) and the glass transition temperature T_(g), ΔT_(x)=T_(x)−T_(g), measured at heating rate of 20 K/min, that is unexpectedly higher than the corresponding Co-free metallic glasses.

In some embodiments, when a ranges from 4 to 30, b ranges from 8 to 10.5, c ranges from 2.25 to 3.75, d ranges from 15.5 to 17, e ranges from 2.5 to 4, the difference between the crystallization temperature T_(x) and the glass transition temperature T_(g), ΔT_(x)=T_(x)−T_(g), measured at heating rate of 20 K/min, is at least 50° C.

FIG. 6 provides calorimetry scans for sample metallic glasses Ni_(68.5-x)Co_(x)Cr₉Ta₃P_(16.25)B_(3.25) in accordance with embodiments of the present disclosure. The glass transition temperature T_(g), crystallization temperature T_(x), solidus temperature T_(s), and liquidus temperature T_(l) are indicated by arrows in FIG. 6. Table 3 lists the glass transition temperature T_(g), crystallization temperature T_(x), solidus temperature T_(s), and liquidus temperature T_(l) along with the respective ΔT_(x) value for sample metallic glasses Ni_(68.5-x)Co_(x)Cr₉Ta₃P_(16.25)B_(3.25) in accordance with embodiments of the present disclosure. FIG. 7 provides a data plot showing the effect of varying the Ni and Co atomic percent on the glass transition temperature T_(g), crystallization temperature T_(x), and difference ΔT_(x)=T_(x)−T_(g) of Ni_(68.5-x)Co_(x)Cr₉Ta₃P_(16.25)B_(3.25) metallic glasses for 0.5≦x≦40.

TABLE 3 Effect of increasing the Co atomic concentration at the expense of Ni on the glass-transition temperature, crystallization temperature, ΔT_(x) (=T_(x) − T_(g)), solidus temperature, and liquidus temperature of Ni_(68.5−x)Co_(x)Cr₉Ta₃P_(16.25)B_(3.25) alloys and metallic glasses Sample Composition T_(g) (° C.) T_(x) (° C.) ΔT_(x) (K) T_(s) (° C.) T_(l) (° C.) 1 Ni_(68.5)Cr₉Ta₃P_(16.25)B_(3.25) 405.5 455.2 49.7 862.4 948.6 2 Ni₆₇Co_(1.5)Cr₉Ta₃P_(16.25)B_(3.25) 402.8 451.0 48.2 858.7 946.3 3 Ni_(65.5)Co₃Cr₉Ta₃P_(16.25)B_(3.25) 404.3 453.5 49.2 858.3 934.4 4 Ni_(63.5)Co₅Cr₉Ta₃P_(16.25)B_(3.25) 408.9 460.8 51.9 864.6 948.0 5 Ni_(58.5)Co₁₀Cr₉Ta₃P_(16.25)B_(3.25) 409.7 465.2 55.5 870.3 947.2 6 Ni_(53.5)Co₁₅Cr₉Ta₃P_(16.25)B_(3.25) 414.4 472.6 58.2 874.8 970.6 7 Ni_(48.5)Co₂₀Cr₉Ta₃P_(16.25)B_(3.25) 419.8 474.6 54.8 881.4 998.1 8 Ni_(43.5)Co₂₅Cr₉Ta₃P_(16.25)B_(3.25) 423.3 477.8 54.5 882.7 961.0 9 Ni_(38.5)Co₃₀Cr₉Ta₃P_(16.25)B_(3.25) 426.0 482.0 56.0 892.1 965.5 10 Ni_(33.5)Co₃₅Cr₉Ta₃P_(16.25)B_(3.25) 431.8 486.0 54.2 897.7 975.3 11 Ni_(28.5)Co₄₀Cr₉Ta₃P_(16.25)B_(3.25) 436.6 490.8 54.4 909.1 998.7

As shown in FIGS. 6 and 7 and Table 3, when the Co content is between 4 and 30 atomic percent, the ΔT_(x) values are unexpectedly larger compared to the value of the Co-free alloy. Specifically, the ΔT_(x) value for the Co-free metallic glass Ni_(68.5)Cr₉Ta₃F_(16.25)B_(3.25) (Sample 1) is 49.7° C., while the ΔT_(x) values for Ni_(68.5-x)Co_(x)Cr₉Ta₃P_(16.25)B_(3.25) metallic glasses for 0.5≦x≦40 (Sample 2-11) are all larger than 50° C., and particularly the value for the metallic glass Ni_(53.5)Co₁₅Cr₉Ta₃P_(16.25)B_(3.25) (Sample 6) is 58.2° C.

In other embodiments, when a ranges from 4 to 30, b ranges from 6 to 8, c ranges from 2 to 3.5, d ranges from 15.5 to 17, e ranges from 2.5 to 4, the difference between the crystallization temperature T_(x) and the glass transition temperature T_(g), ΔT_(x)=T_(x)−T_(g), measured at heating rate of 20 K/min, is at least 45° C.

FIG. 8 provides calorimetry scans for sample metallic glasses Ni_(70.5-x)Co_(x)Cr₇Ta_(2.75)P_(16.25)B_(3.25) in accordance with embodiments of the present disclosure. The glass transition temperature T_(g), crystallization temperature T_(x), solidus temperature T_(s), and liquidus temperature T_(l) are indicated by arrows in FIG. 8. Table 4 lists the glass transition temperature T_(g), crystallization temperature T_(x), solidus temperature T_(s), and liquidus temperature T_(l) along with the respective ΔT_(X) value for sample metallic glasses Ni_(70.5-x)Co_(x)Cr₇Ta_(2.75)P_(16.25)B_(3.25) in accordance with embodiments of the present disclosure. FIG. 9 provides a data plot showing the effect of varying the Ni and Co atomic percent on the glass transition temperature T_(g), crystallization temperature T_(x), and difference ΔT_(x)=T_(x)−T_(g) of Ni_(70.5-x)Co_(x)Cr₇Ta_(2.75)P_(16.25)B_(3.25) metallic glasses for 0.5≦x≦40.

TABLE 4 Effect of increasing the Co atomic concentration at the expense of Ni on the glass-transition temperature, crystallization temperature, ΔT_(x) (=T_(x) − T_(g)), solidus temperature, and liquidus temperature of Ni_(70.5−x)Co_(x)Cr₇Ta_(2.75)P_(16.25)B_(3.25) alloys and metallic glasses Sample Composition T_(g) (° C.) T_(x) (° C.) ΔT_(x) (K) T_(s) (° C.) T_(l) (° C.) 13 Ni_(70.5)Cr₇Ta_(2.75)P_(16.25)B_(3.25) 399.4 440.8 41.4 860.4 911.9 14 Ni₆₉Co_(1.5)Cr₇Ta_(2.75)P_(16.25)B_(3.25) 400.0 443.1 43.1 857.6 939.0 15 Ni_(67.5)Co₃Cr₇Ta_(2.75)P_(16.25)B_(3.25) 398.0 443.7 45.7 859.0 944.3 16 Ni_(65.5)Co₅Cr₇Ta_(2.75)P_(16.25)B_(3.25) 402.3 451.2 48.9 862.9 943.0 17 Ni_(60.5)Co₁₀Cr₇Ta_(2.75)P_(16.25)B_(3.25) 403.1 452.5 49.4 867.3 946.0 18 Ni_(55.5)Co₁₅Cr₇Ta_(2.75)P_(16.25)B_(3.25) 409.3 458.6 49.3 875.6 945.7 19 Ni_(50.5)Co₂₀Cr₇Ta_(2.75)P_(16.25)B_(3.25) 413 460.6 47.6 879.1 949.3 20 Ni_(45.5)Co₂₅Cr₇Ta_(2.75)P_(16.25)B_(3.25) 419.9 466.1 46.2 885.8 970.6 21 Ni_(40.5)Co₃₀Cr₇Ta_(2.75)P_(16.25)B_(3.25) 424.6 469.5 44.9 892.4 1000.2 22 Ni_(45.5)Co₃₅Cr₇Ta_(2.75)P_(16.25)B_(3.25) 422.7 471.1 48.4 901.9 1016.5 23 Ni_(30.5)Co₄₀Cr₇Ta_(2.75)P_(16.25)B_(3.25) 427.5 474.0 46.5 910.0 1038.4

As shown in FIGS. 8 and 9 and Table 4, when the Co atomic percent is between 4 and 30 atomic percent, the ΔT_(x) values are unexpectedly larger compared to the value of the Co-free alloy. Specifically, the ΔT_(x) value for the Co-free metallic glass Ni_(70.5)Cr₇Ta_(2.75)P_(16.25)B_(3.25) (Sample 13) is 41.4° C., while the ΔT_(x) values for Ni_(70.5-x)Co_(x)Cr₇Ta_(2.75)P_(16.25)B_(3.25) metallic glasses for 0.5≦x≦40 (Examples 14-23) are all larger than 42° C., while the ΔT_(x) values for 0.5≦x≦40 (Sample 16-23) are all larger than 45° C. Particularly the ΔT_(x) value for the metallic glass Ni_(60.5)Co₁₀Cr₇Ta_(2.75)P_(16.25)B_(3.25) (Sample 17) is 49.4° C.

Description of Methods of Processing the Sample Alloys

A method for producing the alloy ingots involves inductive melting of the appropriate amounts of elemental constituents in a quartz tube under inert atmosphere. The purity levels of the constituent elements were as follows: Ni 99.995%, Co 99.995%, Cr 99.996%, Ta 99.95%, P 99.9999%, and B 99.5%. The melting crucible may alternatively be a ceramic such as alumina or zirconia, graphite, sintered crystalline silica, or a water-cooled hearth made of copper or silver.

A particular method for producing metallic glass rods from the alloy ingots for the sample alloys of Tables 1 and 2 involves re-melting the alloy ingots in quartz tubes having 0.5-mm thick walls in a furnace at 1100° C. or higher, and in some embodiments, ranging from 1150° C. to 1400° C., under high purity argon and rapidly quenching in a room-temperature water bath. Alternatively, the bath could be ice water or oil. Metallic glass articles can be alternatively formed by injecting or pouring the molten alloy into a metal mold. The mold can be made of copper, brass, or steel, among other materials.

Optionally, prior to producing an metallic glass article, the alloyed ingots may be fluxed with a reducing agent by re-melting the ingots in a quartz tube under inert atmosphere, bringing the alloy melt in contact with the molten reducing agent, and allowing the two melts to interact for about 1000 s at a temperature of about 1200° C. or higher, under inert atmosphere and subsequently water quenching.

Test Methodology for Assessing Glass-Forming Ability

The glass-forming ability of each alloy was assessed by determining the maximum rod diameter in which the amorphous phase of the alloy (i.e. the metallic glass phase) could be formed when processed by the method described above; namely water quenching a quartz tube having 0.5 mm thick walls containing a molten alloy. X-ray diffraction with Cu—Kα radiation was performed to verify the amorphous structure of the alloys.

Test Methodology for Differential Scanning Calorimetry

Differential scanning calorimetry was performed on sample metallic glasses at a scan rate of 20 K/min to determine the glass-transition, crystallization, solidus, and liquidus temperatures of sample metallic glasses.

Test Methodology for Measuring Notch Toughness

The “notch toughness,” defined as the stress intensity factor at crack initiation K_(q), when measured on a 3 mm diameter rod containing a notch with length ranging from 1 to 2 mm and rot radius ranging from 0.1 to 0.15 mm, quantifies the material's ability to resist fracture in the presence of a notch. The notch toughness is a measure of the work required to propagate a crack originating from a notch. A high K_(q) ensures that the material will be tough in the presence of defects.

The notch toughness of sample metallic glasses was performed on 3-mm diameter rods. The rods were notched using a wire saw with a root radius ranging from 0.10 to 0.13 mm to a depth of approximately half the rod diameter. The notched specimens were tested on a 3-point beam configuration with span of 12.7 mm, and with the notched side carefully aligned and facing the opposite side of the center loading point. The critical fracture load was measured by applying a monotonically increasing load at constant cross-head speed of 0.001 mm/s using a screw-driven testing frame. At least three tests were performed, and the variance between tests is included in the notch toughness plots. The stress intensity factor for the geometrical configuration employed here was evaluated using the analysis by Murakimi (Y. Murakami, Stress Intensity Factors Handbook, Vol. 2, Oxford: Pergamon Press, p. 666 (1987)).

The disclosed Ni—Co—Cr—Ta—P—B alloys and metallic glasses with controlled ranges within the disclosed composition range demonstrate a combination of good glass forming ability, high toughness, and large ΔT_(x) values. The disclosed alloys have critical rod diameters of at least 3 mm and up to about 8 mm or greater when processed by the particular method described herein. Certain alloys with very good glass forming ability also have high notch toughness approaching 100 MPa m^(1/2), and ΔT_(x) values approaching 60° C. The combination of good glass-forming ability, high toughness, and large ΔT_(x) values makes the present Ni—Co—Cr—Ta—P—B alloys and metallic glasses comprising Ni—Co—Cr—Ta—P—B alloys excellent candidates for various engineering applications. Among many applications, the disclosed alloys may be used in consumer electronics, dental and medical implants and instruments, luxury goods, and sporting goods applications.

Having described several embodiments, it will be recognized by those skilled in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the invention. Additionally, a number of well-known processes and elements have not been described in order to avoid unnecessarily obscuring the present invention. Accordingly, the above description should not be taken as limiting the scope of the invention.

Those skilled in the art will appreciate that the presently disclosed embodiments teach by way of example and not by limitation. Therefore, the matter contained in the above description or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. The following claims are intended to cover all generic and specific features described herein, as well as all statements of the scope of the present method and system, which, as a matter of language, might be said to fall therebetween 

What is claimed is:
 1. An alloy capable of forming a metallic glass represented by the following formula (subscripts denote atomic percentages): Ni_((100-a-b-c-d-e))Co_(a)Cr_(b)Ta_(c)P_(d)B_(e) where: a ranges from 0.5 to 40, b ranges from 3 to 11, c ranges from 1.5 to 4, d ranges from 14 to 17.5, and e ranges from 2 to 5, and wherein the alloy has a critical rod diameter of at least 3 mm.
 2. The alloy of claim 1 wherein c is determined by x+y·b, where x is between 1.5 and 2 and y is between 0.1 and 0.15.
 3. The alloy of claim 1 wherein a ranges from 0.5 to 30, b ranges from 8 to 10.5, c ranges from 2.25 to 3.75, d ranges from 15.5 to 17, e ranges from 2.5 to 4, and wherein the critical rod diameter of the alloy is at least 5 mm.
 4. The alloy of claim 1 wherein a ranges from 0.5 to 15, b ranges from 8.5 to 10, c ranges from 2.5 to 3.5, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75, and wherein the critical rod diameter of the alloy is at least 6 mm.
 5. The alloy of claim 1 wherein a ranges from 0.5 to 30, b ranges from 6 to 8, c ranges from 2 to 3.5, d ranges from 15.5 to 17, e ranges from 2.5 to 4, and wherein the critical rod diameter of the alloy is at least 5 mm.
 6. The alloy of claim 1 wherein a ranges from 0.5 to 5, b ranges from 6.5 to 7.5, c ranges from 2.25 to 3.25, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75, and wherein the critical rod diameter of the alloy is at least 6 mm.
 7. The alloy of claim 1 wherein the difference between the crystallization temperature Tx and the glass transition temperature Tg, ΔTx=Tx−Tg, measured at heating rate of 20 K/min, is at least 42° C.
 8. The alloy of claim 1 wherein the difference between the crystallization temperature Tx and the glass transition temperature Tg, ΔTx=Tx−Tg, measured at heating rate of 20 K/min, is at least 50° C.
 9. The alloy of claim 1 wherein up to 2 atomic percent of Cr is substituted by Fe, Mn, W, Mo, Ru, Re, Cu, Pd, Pt, or combinations thereof.
 10. The alloy of claim 1 wherein up to 2 atomic percent of Ni is substituted by Fe, Mn, W, Mo, Ru, Re, Cu, Pd, Pt, or combinations thereof.
 11. The alloy of claim 1 wherein up to 1.5 atomic percent of Ta is substituted by Nb, V, or combinations thereof.
 12. A metallic glass comprising an alloy of claim
 1. 13. The metallic glass of claim 12 wherein a ranges from 0.5 to 15, b ranges from 8.5 to 10, c ranges from 2.5 to 3.5, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75; wherein the critical rod diameter of the alloy is at least 6 mm; and wherein the notch toughness is at least 55 MPa m^(1/2).
 14. The metallic glass of claim 12 wherein a ranges from 0.5 to 5, b ranges from 6.5 to 7.5, c ranges from 2.25 to 3.25, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75; wherein the critical rod diameter of the alloy is at least 6 mm; and wherein the notch toughness is at least 80 MPa m^(1/2).
 15. The metallic glass of claim 12 wherein a ranges from 0.5 to 10, b ranges from 8.5 to 10, c ranges from 2.5 to 3.5, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75; wherein the critical rod diameter of the alloy is at least 6 mm; and wherein the notch toughness is at least 60 MPa m^(1/2).
 16. The metallic glass of claim 12 wherein a ranges from 0.5 to 3, b ranges from 6.5 to 7.5, c ranges from 2.25 to 3.25, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75; wherein the critical rod diameter of the alloy is at least 7 mm; and wherein the notch toughness is at least 90 MPa m^(1/2).
 17. A method of producing the metallic glass of claim 12 comprising: melting the alloy into a molten state; and quenching the melt at a cooling rate sufficiently rapid to prevent crystallization of the alloy.
 18. The method of claim 17, further comprising fluxing the melt with a reducing agent prior to quenching.
 19. The method of claim 18, wherein the reducing agent is boron oxide.
 20. The method of claim 17, wherein the melt prior to quenching is heated to at least 1100° C. 